The invention relates to a resistance welding electrode, which has a shaft-shaped holder and an electrode part. The electrode part can be constructed in form of an electrode cap (female) or a rod electrode (male). The respective electrode part is non-positively connected with the associated holder via matching conical surfaces. Optionally, a cooling bore can be provided for a high-performance application.
In conventional welding electrodes of this type, a cone angle of 4 to 7 degrees is used to create the non-positive connection between the holder and electrode part. An interference fit connection is then produced between the holder and the electrode part via the matching conical surfaces. For tolerance reasons, the respective electrode parts must be spaced apart in the axial direction from the respective associated end faces of the holder, so that a gap is present instead of a direct contact to guarantee a tight seat of the electrode part on the holder. Due to the cone angle, this interference fit connection is established with a relatively small relative axial movement between the holder and the associated electrode part. During force transmission, in particular with the pressing force applied during welding by this type of resistance welding electrode, the electrode part can dig into the holder and form bead-shaped peripheral protrusions on the holder. When the electrode parts need to be exchanged, difficulties can arise, such as leaks, a poor interference fit and the risk that the electrode part becomes detached from the holder, as well as an increased consumption of holders which have relatively high manufacturing costs. Additional cost due to lost production can also occur.
DE 101 48 035 B4 discloses an apparatus for resistance welding of workpieces, wherein a welding electrode includes an electrode body, to which an electrode cap is attached or can be attached. The drawing suggests, assuming that the illustration is to scale, that the electrode cap which is placed on the electrode body makes axial contact with the holder via a radial contact surface. Otherwise, the conventional approach is mainly directed to a solution for obtaining information of interest about the electrode temperature more reliably and more cost-effectively. To this end, the welding apparatus has measurement means for measuring the temperature which advantageously reliably measure the temperature of the electrode body and/or the temperature of the electrode cap.